This invention addresses performance degradation in magnetic heads comprised of two or more electrically conductive or dissipative but isolated tape bearing portions. For example, in current full span tape head modules, an insulative adhesive layer is used for bonding closure to the thin film stack portion of the device chip, which contains the magnetic read, write and servo elements, as shown in FIG. 1. Thus, the closure and chip are electrically isolated. Usually the chip itself is connected to ground or other reference voltage in the tape drive, leaving the closure floating. Tape running can then lead to significant closure charging resulting in electrical potential difference between substrate and closure of up to 10s of volts. This is known to contribute to such problems as shorting, alumina pitting, accumulation of adherent debris and others. To prevent closure charging, a device is needed for connecting closure and substrate, thus effectively clamping them at the same potential.
Shorting can be caused by electrical potential differences between conductive components of a magnetic tape head module. Shorting can cause the magnetic head module to malfunction temporarily in the time frame of the short, or cease to operate at all in severe instances of shorting. This is an undesirable effect for the application of reading and writing data to tape, as data can be distorted, destroyed, or recorded/read incorrectly because of the short.
Pitting is a problem encountered in the metals comprising a magnetic tape head module. Pitting is a type of localized corrosion in which metal that is subjected to the conditions that cause pitting develops small holes. Pitting corrosion may be caused by a deficit of oxygen. The area subjected to a lack of oxygen tends to become anodic while the area with an excess of oxygen tends to become cathodic. This leads to galvanic corrosion of the metal around the area of low oxygen.
An accumulation of adherent debris can be caused by potential electrical differences between magnetic tape head module components. This is due to the nature of certain particulate contaminants which are easily polarized to carry a charge. When the charged particle approaches the charged components of the magnetic tape head module, they are attracted to the component and will adhere to the surface, reducing the effectiveness of the component.